1. Field of the Invention
The present invention relates to a method for receiving radio signals by using an access point, and more particularly, to a method for weighing radio signals received by the access point at a second time with a set of weighing factors generated according to radio signals received by the access point at a first time.
2. Description of the Prior Art
Owing to the rapid development of wireless communications technologies, an access points (AP) is becoming one of the most popular communications tools. An AP receives radio signals transmitted by a wireless network subscriber with an appendant antenna.
Please refer to FIG. 1, which is a schematic diagram of a plurality of radio signals 10 projected onto an AP 20 according to the prior art. The AP 20 comprises an antenna 12. An angle θ is included between the AP 20 and wave fronts of the radio signals 10. A distance between two neighboring radio signals (for example, nodes M and N shown in FIG. 1) is d. Because a path difference between any two neighboring radio signals equals d cos θ, if d cos θ is a multiple of the wavelength of the radio signals 10, the intensity of a radio signal projected onto node M equals the intensity of a radio signal projected onto node N. On the contrary, if d cos θ is not a multiple of the wavelength of the radio signals 10, the intensity of a radio signal projected onto node M does not equal the intensity of a radio signal projected onto node N. That is, if d cos θ is a multiple of the wavelength of the radio signals 10, and the intensity of a radio signal projected onto node M is stronger than that of a radio signal projected onto a node neighboring to node M, the intensity of a radio signal projected onto node N is also stronger than that of radio signals projected onto nodes neighboring to node N. Therefore, if the AP 20 receives itself radio signals 10 with only one antenna, a user for the AP 20 has to move the antenna 12 of the AP 20 to a position near node M (or node N) from time to time to get the radio signals having the strongest intensity.
In order to solve the above-mentioned problem, prior art APs adopt diversity antennas to receive the radio signals 10. Please refer to FIG. 2, which is a schematic diagram of another AP 30 according to the prior art. The AP 30 comprises a first antenna 32, a second antenna 34, a controller 36, a switching circuit 38, and a receiver 40. The controller 36 controls the switching circuit 38 to selectively connect the first antenna 32 or the second antenna 34 to the receiver 40 by periodically detecting the power of radio signals received by the first antenna 32 and by the second antenna 34. For example, if the controller 36 detects that the power of radio signals received by the second antenna 34 is greater than that of radio signals received by the first antenna 32 during a first period, the controller 36 then controls the switching circuit 38 to connect the second antenna 34 to the receiver 40. Thus, the receiver 40 of the AP 30 continues to receive radio signals transmitted from the second antenna 34 during the first period. As another example, if the controller 36 detects that the power of radio signals received by the first antenna 32 is greater than that of radio signals received by the second antenna 34 during a second period, the controller 36 then controls the switching circuit 38 to connect the first antenna 32 to the receiver 40. Thus, the receiver 40 of the AP 30 continues to receive radio signals transmitted from the first antenna 32 during the second period. Therefore, with the help of the controller 36 and the switching circuit 38, a user of the AP 30 does not need to move the AP 30 from time to time to receive radio signals with higher intensity. However, because the AP 30 receives radio signals with only one antenna at the same time, the signal-to-noise ratio of radio signals received by the AP 30 is not high.